Power operated rotary knife

ABSTRACT

A rotary knife comprising, an annular blade having a central axis, a blade supporting head assembly supporting the blade for rotation about the axis, a manually grippable handle assembly connected to the head assembly, and a flex shaft drive transmission for driving the blade about the axis. The handle assembly comprises a core, a hand grip surrounding the core, and a connector unit that secures the hand grip to the core. The core has a first end region rigidly fixed with respect to the head assembly and a second end region spaced from the bead assembly. The core defines a drive transmission guiding channel leading toward the blade. The hand grip has a first end region proximal the blade support assembly and a second end region proximal the second core end region. The connector detachably secures the hand grip in fixed relationship with the core. The connector engages the second end regions and is detachable for enabling hand grip removal and replacement.

This application claims the benefit of Provisional application Ser. No.60/157,929, filed Oct. 6, 1999.

FIELD OF THE INVENTION

The present invention relates to a power operated rotary knife that hasan improved handle assembly.

BACKGROUND OF THE INVENTION

Power operated rotary knives have been used in commercial meatprocessing operations to trim fat and connective tissue from meat, trimpieces of meat from bones, and to produce meat slices. Such knives areoften constructed so that they are driven via a long flexible driveshaft. The knife operator wields the knife relatively freely at a meatcutting work station that is remote from the driving motor.

These power operated knives represented a major improvement over use ofhand knives or knives having an integral drive motor. Knife operatorfatigue was greatly reduced, enabling both increased productivity andgreater knife operator comfort. Nevertheless knife operator fatigue wasnot eliminated. Some knives incorporated “take-with” handles that weresized to fit the hands of knife operators using the knives. Thesehandles could be removed from the knives and taken with the knifeoperator after using the knife. Take-with handles reduced fatiguebecause the knife operator could always use a knife with a handle thatwas properly sized. The handles were difficult to install in properalignment with the knife blade.

Some previously known rotary knives were provided with steelingmechanisms. But these were not convenient to use because the knifeoperator had to significantly reposition the knife hand or use two handsto steel the blade.

When the blades of rotary knives must be replaced, the blade is removedfrom its housing on the knife. In many prior art knives, removing theblade was difficult and required the blade housing to be semi-detachedfrom the knife in order for the blade to be removed and replaced. Thisrequired significant operator time and skill to achieve because theblade housing and associated parts had to be properly aligned for theknife to perform optimally. In other knives a special blade removalmechanism was incorporated in the knife. This increased the knife weightand added to the cost of the knives so equipped.

The drive connection between the flexible drive shaft and the bladerotating gearing was typically formed by a square cross section flexshaft end that plugged into a square opening in a drive gear. The bladedrive was disconnected by pulling the flex shaft end out of the drivegear opening. The resultant engagement forces between the faces of theflex shaft end and gear opening had force components that were radiallydirected as well as normal to the radial components. The normal forcecomponents were effective to transmit torque and were of smallermagnitude than the respective engagement forces. Therefore, for a givenamount of torque transmission, the frictional forces resistingdisconnection were great because the frictional forces were proportionalto the engagement force. This tended toward increased difficulty indisconnecting the blade drive.

SUMMARY OF THE INVENTION

The present invention provides a new and improved rotary knifecomprising, an annular blade having a central axis, a blade supportinghead assembly supporting the blade for rotation about the axis, amanually grippable handle assembly connected to the head assembly, and aflex shaft drive transmission for driving the blade about the axis.

An important feature of the invention resides in the handle assemblyconstruction. The handle assembly comprises a core, a hand gripsurrounding the core, and a connector unit that secures the hand grip tothe core. The core has a first end region rigidly fixed with respect tothe head assembly and a second end region spaced from the head assembly.The core defines a drive transmission guiding channel leading toward theblade. The hand grip has a first end region proximal the blade supportassembly and a second end region proximal the second core end region.The connector detachably secures the hand grip in fixed relationshipwith the core. The connector engages the second end regions and isdetachable for enabling hand grip removal and replacement.

The hand grip is provided with an alignment key element that coacts withone of a number of slots that are fixed with respect to the core andhead assembly. The hand grip is manipulated to properly align it withthe head assembly and the alignment key is moved into the appropriateslot before the connector secures the hand grip to the knife.

According to a preferred embodiment, the connector unit engage the coreand clamps the hand grip into fixed relationship with the knife. Theconnector unit comprises a latching mechanism that detachably securesthe drive shaft assembly to the handle assembly in a condition where thedrive shaft assembly and the blade are disengaged.

According to another feature of the invention a steeling mechanism isprovided that is easily accessible to the knife operator so that theoperator can steel the blade without repositioning the knife hand andwithout the need to use two hands to accomplish the steeling procedure.

Still another feature of the invention provides for drive transmittingforces to be transmitted between blade driving gearing and a flex shaftassembly in directions that are normal the radial lines through therotation axis. These driving forces do not have radial components andaccordingly, for a given torque transmission, frictional forcesresisting disconnection of the drive are minimized.

Additional features and advantages of the invention will become apparentfrom the following description of a preferred embodiment made withreference to the accompanying drawings, which form part of thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a knife constructed according to theinvention;

FIG. 2 is a cross sectional view seen approximately from the planeindicated by the line 2—2 of FIG. 1;

FIG. 3 is a view similar to FIG. 2 with parts illustrated in alternativepositions;

FIG. 4 is an exploded perspective view of part of the knife of FIG. 1;

FIG. 5 is an enlarged cross sectional view of part of the knife of FIG.2;

FIG. 6 is a fragmentary cross sectional view seen approximately from theplane indicated by the line 6—6 of FIG. 4 with parts illustrated inalternative positions;

FIG. 7 is a top plan view of part of the knife illustrated in FIG. 4;

FIG. 8 is an enlarged view seen approximately from the plane indicatedby the line 8—8 of FIG. 7;

FIG. 9 is a view seen approximately from the plane indicated by the line9—9 of FIG. 7;

FIG. 10 is an enlarged view seen approximately from the plane indicatedby the line 10—10 of FIG. 9;

FIG. 11 is a view seen approximately from the plane indicated by theline 11—11 of FIG. 5, with parts removed;

FIG. 12 is a view seen approximately from the plane indicated by theline 12—12 of FIG. 11;

FIG. 13 is a perspective view of part of the knife shown in FIGS. 1-3;

FIG. 14 is a view seen approximately from the plane indicated by theline 14—14 of FIG. 1 with parts removed; and,

FIG. 15 is a view seen approximately from the plane indicated by theline 15—15 of FIG. 5.

DESCRIPTION OF THE BEST MODE CONTEMPLATED FOR PRACTICING THE INVENTION

A power operated rotary knife 10 embodying the invention is illustratedby the drawings. The knife 10 comprises an annular blade 12 having acentral axis 14, a blade support assembly 16 supporting the blade forrotation about the axis, a manually grippable handle assembly 20connected to the blade support assembly, and a flex shaft drivetransmission 22 for driving the blade about the axis. The flex shafttransmission 22 comprises a flex shaft assembly 22 a (only part of whichis shown) that extends through the handle assembly 20, and a bladedriving output member 22 b, that is illustrated as a pinion gear,rotatably supported in the blade support assembly and driven from theshaft assembly 22 a to rotate the blade 12.

The blade 12 may be of any suitable or conventional construction andincludes an annular blade section 12 a projecting from the blade supportassembly 16 and an annular enlarged body section defining a ring gear 12b (see FIGS. 2 and 3). The gear 12 b has axially extending teeth bywhich the blade 12 is driven about the axis 14 in mesh with the piniongear 22 b.

The blade support assembly 16 supports the blade 12 and the handleassembly 20. The blade support assembly comprises a head member 30, ablade housing 32, and a clamp assembly 34 for securing the blade andblade housing to the head member. The head member is illustrated asformed by a generally crescent shaped body having a semicircular seatingregion 36 confronting the blade housing, a rectilinear clamp assemblyreceiving socket 38 adjacent the seating region, and a boss 40 thatsurrounds a through bore 42 in the head member and projects oppositelyfrom the slot and seating region.

The blade housing 32 is an annular member for receiving, and rotatablysupporting, the blade 12. The blade housing is split to enable itsresilient expansion for removing and replacing the blade 12. Theillustrated blade housing is seated against the head member seatingregion 36 and positions the blade 12 so that the ring gear 12 b isaccurately positioned for being driven from the pinion gear 22 b. Theblade housing defines a semicircular cut-out area 46 that receives thepinion gear 22 b when the pinion gear and ring gear 12 b mesh.

The blade housing 32 is centered on the axis 14 and has a radially innerblade supporting section 32 a (FIG. 8), a radially outer face 32 b (FIG.9) extending circumferentially about the body, and a body mountingstructure 43 extending circumferentially partially about the body onopposite sides of the body split and disposed between the head member 30and the clamp assembly 34.

Referring to FIGS. 7-10, the body mounting structure 43 defines firstand second axially extending (i.e. parallel to the axis 14) projections43 a disposed on one side of the split, and third and fourth axiallyextending projections 43 b disposed on the other side of the split. Eachprojection extends axially from the blade supporting section to a distalprojection end. Each projection defines a radially outwardly facing,circumferentially extending bearing face 44 confronting the head member30, and a circumferentially extending radially outwardly opening groove45 extending between the respective bearing face 44 and the radiallyouter face 32 b. The projection bearing faces 44 extend parallel to theradially outer face 32 b. The radially outer face 32 b defines a housingbody bearing face portion 46 a (FIG. 7) extending circumferentiallyalong the body mounting structure 43 and confronting the head member.The bearing face 46 a is separated from the bearing faces 44 by thegroove 45.

A first housing mounting slot is defined between the first and secondprojections 43 a. The first mounting slot opens between the distal endsof the first and second projections and extends axially in the mountingstructure to a location substantially adjacent the radially outer face32 b. A second housing mounting slot is defined between the third andfourth projections. The second mounting slot opens between the distalends of the third and fourth projections and extends axially in themounting structure to a location substantially adjacent the radiallyouter face 32 b.

A radially inner bearing face 47 (FIG. 8) extends circumferentiallyalong the radially inner side of the body mounting structure 43 andconfronts the clamp assembly 34. The inner bearing face 47 is locatedaxially between the blade supporting section 32 a and the distalprojection ends. The inner bearing face is axially narrow compared tothe axial extent of either the housing body or the projection bearingfaces. The inner bearing face 47 is constructed and arranged so thatclamping force applied to the inner bearing face is transmitted radiallyand axially through the blade housing to the housing body bearing face46 a and the projection bearing faces 44 for securely clamping the bladehousing in place.

The clamp assembly 34 firmly maintains the blade housing seated againstthe blade support assembly seating region 36 to rigidly position theblade 12 while covering the pinion gear, which might otherwise beexposed to meat, fat, bone chips, etc. that could adversely effect thegearing. The clamp assembly 34 comprises a clamp body 50, and clampingscrews 52. (See FIGS. 1-5, 11 and 12). The clamp body 50 defines asemicircular recess 54 confronting the head member for receiving thepinion gear 22 b, bearing ridges 56 that engage the blade housing 32along the inner bearing face 47 on respective opposite sides of thehousing body split, and clamping screw receiving bosses 58 that projectinto the socket 38 between the projections 43 a and 43 b, respectively.

The clamping screws 52 extend through respective holes in the rear sideof the head member 30 and into respective tapped holes in the bosses 58.The screws are tightened to clamp the body 50 against the blade housing32 and the head member. Each bearing ridge 56 exerts force on the bladehousing that depends on the tension in the respective adjacent clampingscrew 52. If one of the clamping screws is unscrewed slightly, theadjacent bearing ridge exerts diminished clamping force on the bladehousing 32.

The blade housing is formed with an expansion structure 59 that enablesthe housing to resiliently expand, while firmly connected to the headmember, when the blade 12 is removed and replaced. In the illustratedblade housing the expansion structure 59 takes the form of a toolreceiving axial slot in the blade housing outer periphery adjacent thehead member. A screwdriver, or equivalent tool, may be inserted in theslot 59 and levered against the head member to resiliently expand theblade housing diameter. The ability to selectively reduce the clampingforce permits removing and replacing the blade 12 by loosening only theclamping screw nearest the tool slot 59 before expanding the bladehousing diameter. The blade housing thus remains firmly assembled to,and accurately positioned on, the head member during blade replacement.As shown in FIG. 8, the space between the projections 43 b is largerthan the circumferential extent of the boss 58 extending through it sothat the blade housing can be expanded without engaging the boss 58.

In the illustrated knife the clamp assembly 34 carries a blade steelingmechanism 60 that is manually operated periodically to straighten theblade section edge 12 a for maintaining its sharpness. The knife isoperated to rotate the blade 12 about its axis and the knife operatormoves the steel into engagement with the blade to straighten the bladeas it rotates. Referring to FIGS. 2-5, the steeling mechanism 60comprises a supporting body 62, a steel assembly 64 supported by thebody 62 for movement into and away from engagement with the blade 12, amanually operated actuator 66 for shifting the steel assembly from aretracted position into engagement with the blade 12, and a returnspring 68 for returning the steel assembly to its retracted position.

The steel assembly moves toward and away from engagement with the bladealong a first line of action, indicated by the reference character 70.The actuator 66 moves along a second line of action 72 that is neitherparallel to, nor coextending with, the first line of action. In theillustrated knife both lines of action are disposed in or adjacent aplane containing the blade axis 14 and the rotation axis of the piniongear 22 b. The actuator 66 is substantially centered on the head member30 in line with the pinion gear axis 42 a (FIG. 1) so that the actuatoris equally accessible for manual operation to right and left handedknife operators. The steel line of action 70 is offset from the line 72and spaced away from the reach of the operator's knife hand whileholding the knife.

In the illustrated knife, the steel supporting body 62 is formedintegrally with the clamp body and projects radially toward the bladeaxis 14 in the plane of the pinion gear axis of rotation 42 a (See FIG.5). A steel assembly guiding bore 74 extends through the body 62 aboutthe line of action 70. The body 62 also supports the actuator 66 formovement along the line of action 72. While the supporting body 62 isillustrated formed in the same casting as the clamp body 62, the supportbody could as well be a separate member secured to the clamp body.

The steel assembly comprises a plunger 76 that extends through the bore74, and a steel element 80 fixed to the plunger 76. The plunger 76 isformed by a pin 76 a and a screw member 76 b. The pin is generallycylindrical and extends in the bore 74 with one end connected to theelement 80 and the opposite end defining a tapped hole. The screw member76 b has an enlarged diameter and is screwed into the pin 76 a to form ashoulder about the plunger at the juncture of the pin and screw member.

The steel element 80 is a round button-like carbide element having aconvexly curved face 80 a confronting the blade 12. A plunger receivinghole extends through the center of the element 80. The plunger andbutton are bonded together, e.g. by silver soldering. The element face80 a is extremely hard and configured to conform to the configuration ofthe edge of blade section 12 a.

The illustrated return spring 68 is a helical coil spring that iscaptured in the bore 74. The bore 74 is stepped to define an internalshoulder that confronts the plunger shoulder. The spring 68 surroundsthe reduced diameter portion of the plunger and is disposed, in alightly compressed condition, between the confronting shoulders so thatthe plunger is biased to retract the steel element from the blade. Whenthe plunger moves to shift the steel element toward the blade, thespring 82 is further compressed.

The actuator 66 of the illustrated knife comprises a motion transmittinglink 90, a manually engagable operating knob, or button, 92, and a link94 between the link 90 and the steel assembly. The link 90 is mounted onthe steel supporting body 62 for motion along the line of action 72 andnormally projects from the clamp assembly in a direction away from theblade section 12 a. The knob 92 is fixed to the projecting end of thelink 90 where it can easily be engaged and pressed by the knifeoperator's thumb. The knife operator presses the knob 92 and shifts thelink 90 in the direction of the blade section edge 12 a withoutrepositioning the knife in the hand.

The illustrated link 90 is formed by a stiff wire member that comprisesa pair of parallel legs 90 a, 90 b extending between the knob 92 and thelink 94. Each leg passes through a conforming guide bore in thesupporting body 62 so that the link 90 is constrained for motion alongthe line of action 72. The knob 92 is rigidly secured to the legs. Inthe illustrated knife the knob 92 is formed from a plastic material thatis molded onto the legs.

The link 94 is slidingly engaged with steel assembly so that when theknob 92 is depressed, the link 94 shifts along the line of action 72while sliding at a right angle with respect to the steel assembly lineof action 70. As a result, the steel assembly shifts toward the bladesection edge 12 a along its line of action 70. In the illustrated knifethe link 94 is formed continuously with the wire forming the legs 90 andcomprises parallel end regions of the actuator legs 90 a, 90 b,respectively that form a loop around the pin. The end regions are bentto extend at an obtuse angle relative to the line of action 72 so thateach end region extends at 90° with respect to the line of action 70.Each end region slidably engages a pin flange on one side of the plungerso that the sliding engagement between the link 94 and the pin flangeoccurs on diametrically opposite sides of the plunger. The diametricallyspaced engagement locations assure that the actuating forces on thesteel assembly are balanced and plunger binding in the bore 74 isavoided.

When the blade section edge 12 a has been steeled, the knob 92 isreleased and the return spring 68 returns both the steel assembly andactuator to their initial positions. The spring 68 forces the plungeraway from the blade edge along the line of action 70. The element 80 ismoved against the link 94 so that the link slides on the element andshifts along the line of action 72 away from the blade.

The illustrated knife 10 further comprises a depth-of-cut controllinggage 100 that is adjustably positionable relative to the blade section12 a. Referring to FIGS. 1-5, the illustrated gage 100 is detachablyconnected to the clamp assembly 34 and may be removed if the operationsto be performed by the knife do not require a cut-thickness gage. Thegage 100 comprises an annular gage unit 102, and a gage mountingmechanism 104 for securing the gage unit in any one of a number ofpositions on the clamp assembly with the blade axis 14 aligned with theaxis of the gage unit. The gage unit 102 comprises a semicircular gagesection 106 and a supporting body section 110. The body section 110seats on the clamp assembly and supports the gage section cantileverfashion within the annulus formed by the blade 12.

The blade section 12 a and gage section 106 are spaced radially apartrelative to the axis 14 to define an annularly curved intervening space.The gage section 106 comprises a cylindrical wall 106 a that is disposedabout the axis 14 and a radially outwardly extending flange 106 b thatextends from the wall 106 a toward the blade section 12 a. The flange106 b engages meat being cut by the knife and limits the depth of cutthat can be made by the knife. The meat that is cut forms slices thatare no thicker than the distance between the blade edge and the outerperiphery of the flange 106 b. The body section 110 is adjustableaxially relative to the blade 12 to increase or decrease the extent ofthe space between the blade and gage section to control the slicethickness.

The gage body section 110 is integral with the gage section 106 anddefines a semicircular body that confronts the clamp assembly 34. Thebody section 110 defines a radial slot 112 into which the steelsupporting body 62 projects. The body section 110 has shoe-likeprojections 114 on opposite sides of the slot 112 that extend into clampassembly guide slots 116 that conform to the projections 114 and extendalong opposite sides of the steel supporting body 62.

The gage mounting mechanism 104 comprises screws 120 and clamping plates122 (only one of which is shown, see FIG. 4) that coact to detachablysecure the gage 100 to the clamping assembly. The screws 120 freelyextend through generally radially extending bores in the gage bodysection 110. Each bore opens in a respective shoe-like projection 114.The plates 122 are rectangular and each defines a tapped hole forreceiving a respective screw 120. Each plate lies in a respective recessformed in the associated shoe-like projection 114. The plate ends thatare nearest the steel support body 62 extend into undercuts 117 thatextend along the base of the projection 62 on its opposite sides. Whenthe screws 120 that have been threaded into the plates 122 aretightened, each respective plate engages its associated undercut andclamps the gage 100 in place. Loosening the screws allows the gage to beslid along the guide slots 116 to a desired location.

As shown in FIGS. 1-4, the knife 10 also includes a conventional greasecup assembly 140, and a finger guard assembly 142. The grease cupassembly is screwed into a tapped hole in the head member and supplieslubricant to the pinion gear area via passages in the head member. Thefinger guard assembly 142 has a finger guard in the shape of a curvedangle iron fixed to the head member adjacent the blade section edge 12a. One flange of the finger guard depends from the head member tominimize the possibility of the knife operator's fingers slipping alongthe handle assembly 20 and engaging the knife blade. The other flangeengages the head member and is held in place by a pair of mountingscrews.

The handle assembly 20 comprises a core, or frame, member 150 fixed toand extending away from the blade support assembly 16, a hand grip 152surrounding the core member 150, and a connector 154 for detachablysecuring the hand grip to the core member. See FIGS. 1-6. In theillustrated knife, the hand grip is removable so that a knife operatormay take the hand grip away after finishing work with the knife. Thisenables different knife operators to have personalized handle assemblieseven though several operators may use a common knife.

The illustrated core, or frame, member 150 has a first end region 160that is attached to the blade support assembly, a second end region 162spaced from blade support assembly, and forms a drive transmissionchannel for the flex shaft assembly 22 a. In the illustrated knife thecore member is fixed in the head member bore 42 and extends from theblade support assembly along the axis 42 a of the bore 42, i.e. radiallyaway from the blade axis 14. The illustrated core member is tubular andgenerally cylindrical with the drive transmission channel runningthrough it.

The first end region is illustrated as comprising an end flange 170, anexternally threaded mounting section 172, and a stepped internal bore176. The flange 170 extends radially outwardly from the axis 42 a and isnested in a conforming recess in the head member. The radial flange face170 a engages the head member recess to locate the core member relativeto the head member. The core member is screwed into the head member bore42 via the externally threaded mounting section 172 and thread tapped inthe bore 42. The core member is screwed in until the flange 170 bottomsagainst the head member. The core member projects from the boss 40radially away from the blade axis.

A bushing 177 is seated in the bore 176 and the pinion gear 22 b isrotatably supported in the bushing with the pinion gear wheel disposedadjacent the flange 170.

The second end region 162 is illustrated as a cylindrical wall 178surrounding a bore 180 on the axis 42 a that opens to the bore section176. The core member second end region terminates remote from the headmember. The bore 180 serves to guide the flex shaft assembly 22 a intothe bore section 176 for engagement with the pinion gear 22 b.

The hand grip 152 is illustrated as a generally tubular member 181surrounding the core member 150, and a gripping element 182 molded overthe member 181. The hand grip has a first end region 183 proximal theblade support assembly and a second end region 184 proximal the secondcore end region 162. The first end region 183 is constructed andarranged so that the hand grip 152 can be secured to the core member endregion 160 at any of a number of angular positions about the bore axis42 a. For this purpose, the illustrated core member 150 is provided withan external splined section 186 that projects from the boss 40 and theend region 183 is constructed to interfit with the core splines 186. Inthe illustrated hand grip body 181 the end region 183 is provided withfour keys, or internal spline teeth, 188—only one of which is shown—thatproject radially inwardly from the inner face of the hand grip. Thesekeys conform to the external spline teeth on the core member so that thehandle can be positioned at virtually any desired angular position aboutthe axis 42 a. The illustrated hand grip body 181 is constructed from astructurally strong molded plastic material. One or more of the internalspline teeth may be formed in part by a molded-in steel wire segment ifdesired.

The second handgrip end region is formed by a radially outwardlyextending end flange (see FIGS. 1-3 and 14). The end flange 190 servesto anchor a hand strap to the knife 10 and therefore has a substantialradial height. As shown, the flange 190 defines a number of radiallyspaced apart, circumferentially extending slots 192 that can receive andanchor one end of a hand strap. The hand strap end is threaded throughadjacent slots to secure the strap in an adjusted position. The oppositestrap end is suitably secured to the grease cup. The strap is not shown.

The gripping element 182 is molded over the exterior of the hand gripbody from the base of the flange 190 to the end region 183. The grippingelement 182 is formed from a resilient rubber-like material and isergonometrically contoured to fit a knife operator's hand. Axiallyextending bands 196 of cleat-like projections are molded into theelement 182 to minimize the chances of the knife slipping in theoperator's hand. The cleat bands and the operator hand gripping areaterminate well short of the end flange 190. The ergonomic design of thehandle dictates that operator's hand be located close to the head memberand away from the flange.

The connector 154 detachably secures the hand grip 152 to the coremember 150. The illustrated connector is manually operated by the knifeoperator without need for hand tools and permits quick removal andreplacement of the hand grip 152. Referring to FIGS. 1-3 and 13, theillustrated connector is a nut-like member having a hand-grippableannular body 200, a cylindrical section 202 projecting from the body 200into the hand grip, and a bore 204 extending through the connector inalignment with the axis 42 a. The section of the bore 204 extending inthe cylindrical section 202 is tapped so that, after the hand grip 152is assembled to the core member 150, the connector can be inserted intothe hand grip end region 184 and screwed onto an external screw thread206 formed on the core member end region 162.

The threaded core member end region 162 is constructed with four axialslots extending through the thread 206 so that the keys, or splineteeth, in the hand grip end region 183 can move past the threaded endregion 162 as the hand grip 152 is installed on a knife.

The body 200 has an outer diametrical extent that is greater than theinside diameter of the flange 190 and defines a radially inwardlyconverging frustoconical face 210 that extends from the outer peripheryof the body 200 to the cylindrical section 202. The face 210 conforms toa frustoconical face 212 on the handgrip that extends from the end faceof the flange 190 to the hand grip bore 180. When the connector 154 isscrewed onto the core member 150, the face 210 engages the face 212 toboth clamp the hand grip 152 in its assembled position and center thehand grip on the axis 42 a. The illustrated connector 154 defines fingergripping recesses 214 spaced about the outer periphery of the body 200to assure that the connector can be tightly screwed in place by hand.

The illustrated flex shaft assembly 22 a is constructed so that it canbe detachably connected to the knife 10 without drivingly engaging thepinion gear 22 b. The flex shaft assembly is constructed from a flexiblecasing 220, a flexible shaft 222 rotatably disposed in the casing, aknife connecting end assembly 224 that surrounds the flex shaft end, arotatable pinion driving member 226 projecting from the end assembly224, and drive disconnecting spring 228 that surrounds part of the endassembly 224.

The casing and flex shaft may be of any suitable or conventionalconstruction and therefore are not described further. Suffice it to saythat the shaft and casing extend between the knife 10 and a drivingmotor that is remote from the knife and operates to constantly drive theflex shaft within the casing.

The knife connecting end assembly 224 is fixed on the end of the casing220 and surrounds the terminus of the flex shaft adjacent the knife 10.The end assembly comprises a tubular cylindrical guide member 230 thatis fixed with respect to the casing 220, a support member 232 fixed tothe guide member 230, and a latching collar 234 between the end of thecasing 220 and the guide member 230.

The guide member 230 and the support member 232 are fixed with respectto the casing and support rotating elements within them. The member 230has an outer diameter that closely conforms to the inner diameter of thecore member 150 so that when the flex shaft assembly is inserted intothe knife handle, the member 230 accurately guides the pinion drivingmember toward a position for driving the pinion gear 22 b. The guidemember 230 has a larger diameter than the support member 232 so ashoulder 236 is formed by their juncture. The support member 232rotatably supports the pinion driving member 226, with the latterprojecting from the support member.

When the flex shaft assembly is connected to the knife 10 the endassembly 224 is disposed within the core member 150. The disconnectspring 228 is a relatively strong helical spring that surrounds thesupport member 232 and is compressed between the shoulder 236 and aninternal shoulder in the core member bore 180. The spring 228 biases theend assembly 224 in a direction away from the pinion gear 22 b.

The illustrated latching collar 234 is constructed and arranged tomaintain the flex shaft assembly attached to the knife 10 both in acondition where the blade is driven and where the blade is not driven.The illustrated latching collar comprises a latching ring 240 that isintegral with the collar and functions to latch the flex shaft assemblyto the knife in the drive disconnected mode, and a lever mechanism 242for use in connecting the blade to the drive.

In the illustrated knife 10 the connector 154 serves not only to securethe hand grip 152 to the knife, but also to detachably secure the flexshaft assembly 22 a to the knife and to enable engagement anddisengagement of the flex shaft assembly and the pinion gear 22 b. Theillustrated connector 154 is constructed and arranged to include alatching assembly 246 in the body 200 (see FIG. 13). The latchingassembly comprises a latching plate 250 supported in a slot 251 thatextends into the body 200 transverse to the axis 42 a, springs 252, anda retainer pin 254 that secures the plate 250 in the body 200. The plateis generally planar and has a circular opening 256 that conforms to theconnector bore 204. One plate end 257 projects from the slot 251 whilethe opposite plate end 258 extends toward the closed slot end beyond theconnector bore 204. The springs 252 are disposed between the base of theslot and the adjacent plate end 258. In the illustrated mechanism, thesprings 252 are small helical coil springs that are compressed betweenthe slot base and the plate and urge the plate to a position where partof the plate opening 256 is misaligned with, and partially obstructs,the connector bore 204. The retainer pin 254 extends into the body 200through the slot 251 and an elongated slot 260 in the plate. Theretainer pin 254 engages one end of the slot 260 to prevent the platefrom being displaced from the slot 251 by the springs 252.

When the flex shaft assembly is inserted into the knife handle, the flexshaft assembly is thrust into the knife handle so that the shaft endassembly 224 moves into the handle bore 180 and the disconnect spring228 is compressed. As the collar 234 enters the connector bore 204 thelatching ring 240 is forced in to engagement with the plate 250. Theleading side of the latching ring is frustoconical and as it moves intothe bore 204 it wedges the plate 250 toward the bottom of the slot 251against the springs 252. When the latching ring passes the plate, thesprings 252 force the plate to its initial position where it againpartly obstructs the bore 204. The trailing side of the latching ring isplanar and extends radially relative to the axis 42 a so that, when theflex shaft assembly tends to be withdrawn from the knife, the plate 250and latching ring trailing side engage and prevent removal. When thelatch plate 250 and the latching ring 240 are engaged as described, theflex shaft assembly and pinion gear are not drivingly connected. Thus,the flex shaft assembly may be latched to the knife handle withoutdriving the blade.

The lever mechanism 242 enables the flex shaft assembly to be drivinglyconnected to, and disconnected from, the knife blade under the controlof the knife operator. The mechanism 242 comprises a pivot pin 262connected to the collar 234 and a lever 264 movable about the pivot pinfor moving the flex shaft assembly to and away from the connectedposition. The illustrated pivot pin 262 is integral with the collar andconnected to the collar by legs 266. The legs project away from thecollar so that the pin is supported with its axis extending at rightangles to the plane of the axis 42 a and is spaced laterally away fromthe axis 42 a.

The illustrated lever 264 is an elongated sheet metal member that isbent to form a semi-cylindrical bearing section 270 that engages thepivot pin 262, a cam face 272, and an arm section 274 that projects awayfrom the cam face along the knife handle.

When the flex shaft assembly is latched to the knife and the operatordecides to engage the flex shaft assembly with the blade, the lever armsection 274 is aligned with a slot 276 formed in the hand grip flange190 and the flex shaft assembly 22 a is manually thrust fully into thehandle bore 180 until the cam face 272 is located adjacent the connectorface 210. The collar and flex shaft end assembly shift further into thehandle to connect the end assembly with the pinion gear. The lever armsection 274 moves freely into proximity with the hand grip 152, asillustrated in FIG. 3. The operator squeezes the lever arm sectionagainst the hand grip. The cam face 272 engages the connector face 210.The disconnect spring 228 is further compressed as the end assembly 224moves into the handle so the end assembly is biased away from theconnected position.

So long as the operator continues to grip the knife handle and lever armsection 274, the flex shaft assembly and the pinion gear remainconnected. When the operator releases the lever arm, the disconnectspring 228 forces the end assembly away from its connected positionuntil the latch plate 250 and the latching ring 240 re-engage with theflex shaft assembly in its disconnected position, but latched to theknife. The lever cam face 272 rides along the frustoconical connectorface 212 assuring that the lever arm section is separated from thehandle and does not impede the disconnecting motion of the end assembly.

The latching assembly is manually operable to enable removal of the flexshaft assembly from the knife. In the illustrated knife, the knifeoperator depresses the plate end 257 by finger pressure to align theplate opening 256 with the connector bore 204 against the spring force.The flex shaft drive end is withdrawn through the bore 204 and alignedopening 256 without interference.

The drive coupling arrangement for transmitting drive from the flexshaft assembly to the pinion gear is so constructed and arranged thatthe force exerted on the end assembly by the disconnect spring 228 ismore than sufficient to separate the pinion gear 22 b from the piniondriving member 226. Referring to FIGS. 2, 3, 5 and 15, drivetransmitting surfaces 280, fixed with respect to the pinion gear, extendgenerally in the direction of the axis 42 a, with at least a portion ofeach drive transmitting surface disposed on a radial line passingsubstantially through the axis. In the illustrated knife the pinion gearis formed with a hollow supporting shaft 282 that is rotatable in thebearing 177 (FIG. 15). The drive transmitting surfaces 280 are formed onrespective lobe-like projections 284 that extend radially inwardly fromthe inner surface of the pinion shaft 282. In the illustrated knife,four equally spaced projections are disposed about the axis 42 a. Theprojections extend circumferentially a relatively short distance aboutthe axis 42 a so that they are spaced relatively widely apart.

The rotatable pinion driving member 226 defines drive transmittingsurfaces 290 engaging respective drive transmitting surfaces 280 on thepinion gear. Each surface 290 engages a surface 280 along at least partof its axial extent. The drive transmitting surfaces have at least aportion disposed on a radial line passing substantially through the axis42 a when the drive transmitting surfaces 280, 290 are engaged. In theillustrated knife, the pinion driving member 226 has a generallycylindrical body and the drive transmitting surfaces 290 are formed onlobe-like projections 292 that extend radially away from the body. Thereare four projections 292 and when the end assembly and pinion gear areconnected, the projections 292 move axially into the spaces between thepinion shaft projections 284 and into driving engagement with thesurfaces 280.

The disconnect spring 228 biases the surfaces 280, 290 away fromengagement with each other in that the spring 228 urges the surfaces 290in a direction axially out of the pinion shaft 282. The lever mechanism242, when gripped by the knife operator, is effective to overcome thedisconnect spring bias and maintain the driving member within the pinionshaft 282, but when the lever mechanism is no longer gripped, the springforce disconnects the drive surfaces.

The radially extending drive transmitting surfaces 280, 290 engage withthe driving forces transmitted between them along lines of action thathave no component extending radially with respect to the axis 42 a. Theresult is that the frictional forces resisting separation of the drivesurfaces are minimized for any given amount of torque transmission.

This is to be contrasted with other forms of drive connection where, forexample, a square cross section drive transmitting member is insertedinto a square hole in a pinion shaft. In that case, the forcetransmitted between engaged driving faces is along a line of actionhaving a radial component and a component normal to the radialcomponent. The frictional forces between the engaged faces areproportional to the resultant force transmitted by the faces. Thesefrictional forces are larger than the frictional forces attributable tothe component forces.

The illustrated knife 10 employs a lever mechanism 242 for use inconnectingand disconnecting the flex shaft assembly and pinion gear; butother constructions can be employed. For example, the collar 234 can beprovided with a second latching ring—constructed like the latching ring240—in place of the lever mechanism. In such an arrangement, the flexshaft assembly is thrust into the bore 204 and latched in thedisconnected position as described above. When the operator decides toconnect the flex shaft assembly to the pinion gear, the shaft assemblyis thrust further into the bore 204 until the second latching ring haspassed the latching plate 250. The latching plate 250 and the secondlatching ring coact just like the latching plate and latching ring 250so that the flex shaft assembly is latched to the knife in its connectedposition. When the knife operator wishes to disconnect the flex shaftassembly the latching plate is depressed to unlatch the second latchingring.

While only a single embodiment of the invention has been illustrated anddescribed, various adaptations, modifications, and uses of the inventionmay occur to those skilled in the art to which the invention relates.The intention is to cover hereby, all such adaptations, modifications,and uses that fall within the scope or spirit of the appended claims.

What is claimed is:
 1. A rotary knife comprising: an annular bladehaving a central axis; a blade support assembly supporting said bladefor rotation about said axis; a manually grippable handle assemblyconnected to said blade support assembly; a drive transmission fordriving said blade about said axis; said handle assembly comprising: acore having a first end region rigidly fixed with respect to said bladesupport assembly and a second end region spaced from said blade supportassembly, said core defining a drive transmission guiding channelleading toward said blade; a hand grip surrounding said core, said handgrip having a first end region proximal said blade support assembly anda second end region proximal said second core end region; and, aconnector for detachably securing said hand grip in fixed relationshipwith said core, said connector engaging said second end regions anddetachable for enabling removal and replacement of said hand grip. 2.The knife claimed in claim 1 wherein said connector comprises at leastpart of a coupling mechanism for detachably securing said drivetransmission to said handle assembly.
 3. The knife claimed in claim 2wherein said connector is threaded to one of said core or hand grip andbears on the other of said core or hand grip.
 4. The knife claimed inclaim 1 wherein said handle assembly has a longitudinal axis extendingaway from said blade support assembly and further comprising radialalignment structure for supporting said hand grip in one of a pluralityof hand grip positions spaced angularly apart about said handle assemblylongitudinal axis.
 5. The knife, claimed in claim 1 wherein saidconnector defines an opening aligned with said guiding channel.
 6. Theknife, claimed in claim 1 wherein said drive transmission comprises aflex shaft assembly having a flexible rotatable drive shaft and a driveshaft housing assembly, said knife further comprising a latchingmechanism for detachably connecting said flex shaft assembly to theknife.
 7. The knife claimed in claim 1 wherein said hand grip comprisesrigid tubular base member and a relatively soft resilient grippablesection surrounding said base member.
 8. A rotary knife comprising, anannular blade having a central axis, a blade supporting assemblysupporting the blade for rotation about the axis, a manually grippablehandle assembly connected to the blade support assembly, and a flexshaft drive transmission for driving the blade about the axis, saidhandle assembly comprising a core, a hand grip surrounding the core, anda connector unit that secures the hand grip to the core, said corehaving a first end region rigidly fixed with respect to the bladesupport assembly and a second end region spaced from said blade supportassembly [extending therefrom to a core end distal the blade supportassembly], said core defining a drive transmission guiding channelleading toward the blade, said connector detachably securing the handgrip in fixed relationship with the core adjacent the distal core end.9. The knife claimed in claim 8 wherein said core is a tubular member,said connector threaded to said distal core end for clamping said handgrip in place with respect to said core and support assembly.